Kissinger–Akahira–Sunose Models Research Articles

Ammonium Perchlorate-Based Energetic Molecular Perovskite DAP-4 Deposited on CNTs: Catalytic Decomposition Behavior, Mechanisms, and Kinetics

Energetic molecular perovskite with superior decomposition enthalpy and high oxidizing ability is the out coming potential oxidizer in advanced highly energetic systems. In this study, perovskite DAP-4 was fabricated by molecular assembly stagey; multi wall carbon nanotubes (MWCNTs) were employed as a potential catalyst for thermal decomposition of DAP-4. Encapsulation method was adopted to develop DAP-4@MWCNTs nanocomposite. MWCNTs experienced superior catalytic effect on DAP-4 decomposition. MWCNTs offered an increase in DAP-4 decomposition enthalpy by 37.5%, with decrease in its main decomposition temperature by 6 °C. Decomposition kinetics were investigated via isoconversional (model free) and model fitting including Kissinger, Kissinger–Akahira–Sunose (KAS), and integral isoconversional method of Ozawa, Flyn and Wall (FWO). DAP-4@MWCNTs demonstrated apparent activation energy of 135.3 ± 3.9 kJ/mol compared with 142.3 ± 4.15 kJ/mol for pure DAP-4 via KAS model. While DAP-4 demonstrated decomposition reaction of first order reaction model (F1); DAP-4@MWCNTs demonstrated decomposition reaction of third order model (F3). Moreover, a possible catalytic mechanism of MWCNTs via induced holes and electrons to enhance electron transfer ability. This work could promote the application of DAP-4 in the field of solid rocket propellant.

Thermal Oxidative Degradation of Pure Cu2S and Industrial White Metal

The kinetics of the thermal oxidation of white metal and Cu2S have been studied by thermogravimetric analysis (TG), which was carried out under atmospheric oxidative conditions (O2 100%) with heating rates of 5, 10, 15 and 20 °C min−1. Each experiment was performed three times, the indicated values being the average of the three experiments. The experimental data were evaluated using isoconversional models based on the Arrhenius equation. The models are constructed using first-order mechanisms in the reactions and therefore, since most of them present adequate regression coefficients, it can be verified that order 1 is the most predominant order among the reactions found. In addition, the Kissinger–Akahira–Sunose model, which has the highest regression coefficient, is considered to be the most optimal. Similar behavior was recorded between Cu2S and white metal, as well as a similar regular increase in the apparent activation energy (Ea) of 10–30 kJ mol−1 for both materials. The reactions that took place during the oxidation of white metal and Cu2S were determined using a computational model based on thermodynamics developed in this work. The identified phases include CuSO4, Cu2SO4, Cu2O, CuO, CuO·CuSO4.

Pyrolysis kinetics and thermal degradation characteristics of coffee, date seed, and prickly pear wastes and their blends

This study's objective was to emphasize the renewable lignocellulosic biomasses' energy potential by thermally describing them. The TG/DTG/DTA procedures were used to examine the thermal pyrolysis behavior of coffee wastes (CW), date seeds (DSM), prickly pears (PP), and two blends (50%CW/50%DSM and 33.3%CW/33.3%DSM/33.3%PP by weight), and their physico-chemical compositions were identified and assessed. The activation energy (E) of all tested samples was predicted using iso-conversional models like Friedman (FR), Starink (ST), Kissinger-Akahira-Sunose (KAS), and Ozawa-Flynn-Wall (OFW), and the frequency factor (A) was calculated based on the acquired (E) values utilizing the chemical reaction mechanisms (C1–C8). SEM, EDX, and FTIR techniques were used to examine the microstructure, mineralogy, and functional group present in the studied samples. Every DTG profile displayed a rightward shift when the heating rate (β) rose to higher temperatures. The difference in the average activation energy (Eav) values between the ST, OFW, and KAS models, except for the blend (1), does not surpass 5 kJ/mole. Increases in the (β) value, particularly for blends, were significantly correlated with increases in the maximum pyrolysis rate (−RP), pyrolysis index (CPI), pyrolysis stability index (RW), and volatile release index (Ddev). The ΔGav discrepancies between the results from all kinetic models for all samples varied from 1 to 7 kJ/mole. A little potential energy barrier was noticed when comparing the (Eav) to the average enthalpy (ΔHav).

Novel ammonium perchlorate/RDX co-crystal: bespoke energetic materials with tailored decomposition kinetics

ABSTRACT Ammonium perchlorate/cyclo-trimethylene-trinitramine (AP/RDX) co-crystal was accomplished via solvent sublimation. Proper dispersion of AP within RDX matrix was verified using EDAX detector. AP/RDX co-crystal experienced the evolution of novel crystalline structure with superior thermal behavior. AP/RDX co-crystal experienced an increase in RDX decomposition enthalpy by 70.6%. Furthermore, it revealed decrease in RDX activation energy by −60.0% and −59.5% using Kissinger and Kissinger–Akahira–Sunose models, respectively. AP could bind effectively with RDX via hydrogen bonding and strong dipole–dipole interaction. This electrostatic bonding could be weakened at low temperature with the release of reactive species (ammonia and percholoric acid) that would catalyze RDX decomposition.

Thermogravimetric analysis and kinetic modeling of the co-pyrolysis of a bituminous coal and poplar wood

The co-pyrolysis of coal and biomass has proven to be a promising route to produce liquid and gaseous fuels as well as specific value-added chemicals while contributing to mitigating CO2 emissions. The interactions between the co-processed feedstocks, however, need to be elucidated to support the development of such a thermochemical conversion process. In this context, the present work covers the kinetic analysis of the co-pyrolysis of a bituminous coal with poplar wood. In this research, biomass was blended with coal at two different mass ratios (10% (mass) and 20% (mass)). Thermogravimetric analyses were carried out with pure and blended samples at four heating rates (5, 10, 15 and 30 °C·min−1). A direct comparison of experimental and theoretical results (based on a simple additivity rule) failed to yield a clear-cut conclusion regarding the existence of synergistic effects. Kinetic analyses have therefore been achieved using two model-free methods (the Ozawa–Flynn–Wall and Kissinger–Akahira–Sunose models) to estimate the rate constant parameters related to the pyrolysis process. A significant decrease of the activation energy has thus been observed when adding wood to coal (activation energies associated with the blend containing 20% (mass) of biomass being even lower than those estimated for pure wood at low conversion degrees). This trend was attributed to the possible presence of synergies whose related mechanisms are discussed. The rate constant parameters derived by means of the two tested models were finally used to simulate the evolution of the conversion degree of each sample as a function of the temperature, thus leading to a satisfying agreement between measured and simulated data.

Gasification Characteristics and Kinetics of Lipid-Extracted Nannochloropsis gaditana

A thermal behavior study of lipid-extracted Nannochloropsis gaditana (LEA) was performed in a thermogravimetric analyzer. The study was performed by heating the sample under different heating rates (5, 10, and 15 °C/min) from room temperature to 1000 °C using N2 gas as the medium. This is crucial for thermal stability studies in a kinetic control regime. The following three stages of chemical decompositions were found: (1) moisture removal (2) devolatilization (3) fixed carbon decomposition; maximum decomposition was observed at the second stage. Activation energies of the LEA were studied using the Flynn–Wall–Ozawa model and Kissinger–Akahira–Sunose model. Main sample decomposition was observed from 100–700 °C during volatile matter evaporation. The thermal behavior study findings were used for the gasification of the sample with air to study the effect of varying reaction parameters on the compositions of the synthesis gas yield. Maximum H2 yield was found at 700 °C and 0.7 g, which were 51.2 mol% and 50.6 mol%, respectively. From the study, it was found that LEA is suitable to be used as feedstock in gasification for synthesis gas production.

Experimental Investigation of Kinetic Parameters of Bamboo and Bamboo Biochar Using Thermogravimetric Analysis Under Non-isothermal Conditions

The present investigation deals with the thermogravimetric analysis of bamboo and bamboo biochar in an inert environment at 10, 20, and 30 °C/min. In addition, vacuum pyrolysis was used for the bamboo biochar. The FWO (Flynn–Wall–Ozawa) and KAS (Kissinger–Akahira–Sunose) methods were used to determine thermodynamic and kinetic parameters within the active pyrolysis zone. Thermal degradation of bamboo biomass undergoes several steps of loss of mass, including moisture loss, and passive and active pyrolysis. Between 180 and 395 °C, the active pyrolysis zone accounted for 50 to 55% of the mass loss. Furthermore, in both FWO and KAS models, bamboo biochar had lower activation energy values (99.23 and 96.07 kJ/mol) than bamboo biomass (262.5303 and 266.62 kJ/mol). The study’s study on bamboo and its biochar revealed a significant opportunity in the agro-industry for designing and building pyrolysis reactors for long-term biofuel generation.

Waste biomass valorisation of Bambusa vulgaris dust and Delonix regia pods: Characterization and kinetic study

The present study is focused to biomass-based exploration via physiochemical characterization of biomass waste Bambusa vulgaris dust (BD) and Delonix regia pods peels (DRP) for the enhancement of biofuels production using suitable methods. Physiochemical characteristics of the selected biomass wastes were determined using proximate and ultimate analysis, FTIR spectroscopy, elemental analysis, TGA (thermo-gravimetric analysis), and XRD (X-ray diffraction). Ultimate analysis result of BD showed good amount of lignin (18–27 %) and cellulose (48–72 %) present in it. Both BD and DRP biomasses showed the higher calorific value of ∼16 MJ/kg. Model free methods like Kissinger-Akahira-Sunose (KAS) and Flynn-Wall-Ozawa (FWO) were applied for the determination of kinetic parameters. The calculated average activation energy was 85.19 and 143.96 kJ/mol using KAS model and 84.82 and 143.32 kJ/mol using FWO model for BD and DRP biomass, respectively.

Hydrogen-Rich Syngas and Biochar Production by Non-Catalytic Valorization of Date Palm Seeds

Pyrolysis has been demonstrated to be a highly effective thermochemical process for converting complex biomaterials into biochar and syngas rich in hydrogen. The pyrolysis of mixed date palm seeds from Saudi Arabia was conducted using a fixed-bed pyrolyzer that was custom made for the purpose. The influence of the pyrolysis temperature (200–1000 °C) on the various physicochemical parameters of the date seed biochar generated through the pyrolysis process and the hydrogen-rich syngas was investigated. Proximate and ultimate analyses indicated a high carbon content in the lignocellulosic constituents such as cellulose, hemicellulose, and lignin. Using energy-dispersive X-ray (EDX) analysis, it was discovered that the elemental composition of biochar changes with the pyrolysis temperature. The date seeds pyrolyzed at 800 °C were found to have the maximum carbon concentration, with 97.99% of the total carbon content. The analysis of the biochar indicated a high concentration of carbon, as well as magnesium and potassium. There was a potential for the production of hydrogen-rich syngas, which increased with the pyrolysis temperature. At 1000 °C, the highest hydrogen and carbon monoxide compositions of 40 mol% and 32 mol%, respectively, were obtained. The kinetic data of the date seed pyrolysis were fitted using linearized model-free methods, such as Friedman, Flynn–Wall–Ozawa (FWO) and Kissinger–Akahira–Sunose (KAS), as well as non-linear methods such as Vyazovkin and advanced Vyazovkin. The activation energies obtained from Friedman, FWO, and KAS varied in the range of 30–75 kJ/mol, 30–65 kJ/mol, and 30–40 kJ/mol, respectively, while those of Vyazovkin and advanced Vyazovkin were found in the range of 25–30 kJ/mol, and 30–70 kJ/mol, respectively. The analysis showed that the FWO and KAS models show smaller variation compared to Friedman.

Catalytic pyrolysis of coconut oil with Ni/SBA-15 for the production of bio jet fuel.

Catalytic pyrolysis of vegetable oil is one of the potential routes to convert oil to drop-in biofuels, known as renewable hydrocarbons. In this paper, we explored catalytic pyrolysis of coconut oil using SBA-15 impregnated with Ni in proportions of 1% to 5% to produce sustainable aviation fuel. The catalysts were synthesized, calcined and then characterized by XRD, FTIR, SEM, and EDS. In order to better understand the behavior of this process, thermal and kinetic studies were carried out by thermogravimetry. The TG curves of vegetable oil with (10%) and without catalysts were obtained at heating rates of 5, 15 and 20 °C min−1, in the temperature range between 30 and 600 °C. The kinetic parameters were calculated by the Ozawa–Flynn–Wall (OFW) and Kissinger–Akahira–Sunose (KAS) methods. In the kinetic study, lower heat rates promoted higher conversions and the KAS model suits the process. The results calculated for the OC sample using the two kinetic models showed an increase in the Ea energy as the conversion progressed to a certain point. Catalytic pyrolysis experiments were performed in a one-stage tubular reactor at 500 °C with a catalyst loading of 10 wt% on the basis of mass of oil. The catalyst with 5% Ni showed greater presence of hydrocarbons and greater formation of water, indicating that the deoxygenation process occurred through decarbonylation. With this, the present study was successful in the development of methodologies for obtaining hydrocarbons with a composition close to that of drop-in fuels, compared to the process carried out with vegetable oil in the absence of catalysts.

Synergistic Effects on the Co-pyrolysis of Agricultural Wastes and Sewage Sludge at Various Ratios.

This study investigated the co-pyrolysis of blends of sewage sludge (SS) with rice husk (RH) and with hemp straw (HS) at different ratios by using thermogravimetry (TG) and its rate (DTG, derivative TG) analysis at heating rates of 10, 20, and 30 K/min. The resulting kinetic parameters of activation energy (Ea) were calculated by both Flynn–Wall–Ozawa and Kissinger–Akahira–Sunose models, followed by comparison of experimental values with calculated values to reveal the synergistic effects of SS/RH and SS/HS. With increasing additions of RH or HS to SS, a gradual decreasing trend in the experimental pyrolysis temperature range was evident, ranging from 144.5 to 95.2 °C for SS/RH and from 144.5 to 88.8 °C for SS/RH. Moreover, such temperature ranges were 6.7–20.4 °C less than the calculated values at the same blending ratio. The fitting results of the two kinetic models showed that with the same SS mass ratio, the experimental Ea* (average activation energy) of both SS/RH and SS/HS were less than the calculated Ea*. Especially, the experimental Ea* of 7SS–3RH was lower around 43.8% than the calculated Ea*, whereas the experimental Ea* of 3SS–7HS was lower by about 39.4% than the calculated Ea*. Synergistic analysis demonstrated that the co-pyrolysis of RH or HS with SS at various mass ratios presented obvious synergistic effects and then the decrease of Ea. The mechanism experiment showed that the co-pyrolysis of SS/HS may promote the decrease of Ea by changing the co-pyrolysis gas products or by increasing the overflow of volatile matter and then forming intermediate transition products, while SS/RH may accelerate the decrease of the Ea by using an appropriate K addition ratio from RH as a metal catalyst.

Determination of the Kinetics and Thermodynamic Parameters of Lignocellulosic Biomass Subjected to the Torrefaction Process.

The torrefaction process upgrades biomass characteristics and produces solid biofuels that are coal-like in their properties. Kinetics analysis is important for the determination of the appropriate torrefaction condition to obtain the best utilization possible. In this study, the kinetics (Friedman (FR) and Kissinger–Akahira–Sunose (KAS) isoconversional methods) of two final products of lignocellulosic feedstocks, miscanthus (Miscanthus x giganteus) and hops waste (Humulus Lupulus), were studied under different heating rates (10, 15, and 20 °C/min) using thermogravimetry (TGA) under air atmosphere as the main method to investigate. The results of proximate and ultimate analysis showed an increase in HHV values, carbon content, and fixed carbon content, followed by a decrease in the VM and O/C ratios for both torrefied biomasses, respectively. FTIR spectra confirmed the chemical changes during the torrefaction process, and they corresponded to the TGA results. The average Eα for torrefied miscanthus increased with the conversion degree for both models (25–254 kJ/mol for FR and 47–239 kJ/mol for the KAS model). The same trend was noticed for the torrefied hops waste samples; the values were within the range of 14–224 kJ/mol and 60–221 kJ/mol for the FR and KAS models, respectively. Overall, the Ea values for the torrefied biomass were much higher than for raw biomass, which was due to the different compositions of the torrefied material. Therefore, it can be concluded that both torrefied products can be used as a potential biofuel source.

Determination of the Thermodynamic Parameters of the Pyrolysis Process of Post-Consumption Thermoplastics by Non-Isothermal Thermogravimetric Analysis.

Currently, the pyrolysis process is an important technology for the final treatment of plastic waste worldwide. For this reason, knowing in detail the chemical process and the thermodynamics that accompany cracking reactions is of utmost importance. The present study aims to determine the thermodynamic parameters of the degradation process of conventional thermoplastics (polystyrene (PS), polyethylene terephthalate (PET), high-density polyethylene (HDPE), polypropylene (PP) and polyvinyl chloride (PVC)) from the study of their chemical kinetics by thermogravimetric analysis (TG). Non-isothermal thermogravimetry was performed at three heating rates from room temperature to 550 °C with an inert nitrogen atmosphere with a flow of 20 mL min−1. Once the TG data is obtained, an analysis is carried out with the isoconversional models of Friedman (FR), Kissinger–Akahira–Sunose (KAS), and Flynn–Wall–Ozawa (FWO) in order to determine the one that best fits the experimental data, and with this, the calculation of the activation energy and the pre-exponential factor is performed. The validation of the model was carried out using the correlation factor, determining that the KAS model is the one that best adjusts for the post-consumer thermoplastic degradation process at the three heating rates. With the use of the kinetic parameters, the variation of the Gibbs free energy is determined in each of the cases, where it is necessary that for structures containing aromatic groups a lower energy is presented, which implies a relative ease of degradation compared to the linear structures.

Catalytic co-pyrolysis of wet-torrefied bamboo sawdust and plastic over the zeolite HY: Synergism and kinetics

In this study, the catalytic co-pyrolysis (CCP) of wet-torrefied bamboo sawdust (TB) and linear low-density polyethylene (LLDPE) over zeolites was carried out using the thermogravimetric analyzer. The analysis was carried out at four different heating rates (5–40 °C min−1) and under an inert (Ar) atmosphere. Four degradation stages were observed in the CCP of TB and LLDPE blends, the first stage being moisture removal. The peak decomposition temperature of catalytic pyrolysis (CP) of LLDPE over FAU was reduced by 251 °C as compared to that over HZSM-5 and the enhancement can be attributed to the topology of HY. The activation energies were calculated using isoconversional models: Kissinger–Akahira–Sunose model (KAS), Ozawa–Flynn–Wall model (OFW), and Friedman model (FM). The average activation energies (Eα) of the blends TBL3:1, TBL1:1, and TBL1:3 (TBL: Blend of torrefied biomass and LLDPE) were 171, 128, and 117 kJ mol−1, respectively, using the KAS model. The Eα of the blends was much lower as compared to that of TB, indicating a clear synergism. A multistep mechanism was observed in both CP of individual samples and CCP of blends, as analyzed by Criado's master plot. For example, the CCP of TBL1:3 followed geometric (volume) contraction (R3) and first-order reaction models at low and high conversions, respectively.

Thermal studies of biomass obtained from the seeds of Syzygium cumini and Cassia fistula L. and peel of Cassia fistula L. fruit

The potential of thermo-chemical performance of three biomass materials namely Syzygium cumini seeds (JP), Cassia fistula L. seed (AT), and Cassia fistula L. fruit peels (AP) has been investigated in detail in the present study. Thermo-gravimetric analysis (TGA) was conducted for pyrolysis kinetic parameters at various temperatures (heating rates). Five temperatures (10, 15, 20, 25, and 30 °C/min) and two model-free techniques (especially Flynn-Wall-Ozawa (FWO) and Kissinger-Akahira-Sunose (KAS)) were applied to evaluate the response. It was found that the respective average activation energies were 222.66, 200.82, and 224.57 kJ/mol for JP, AT, and AP, respectively, in the case of the FWO model, while the average activation energies 223.49, 201.19, and 227.43 kJ/mol were obtained by using the KAS model. The activation energy, enthalpy, and pre-exponential factor for the studied biomass materials are shown in the order of AP > JP > AT in both these models. Moreover, the highest values of pre-exponential factor were found for JP in FWO (1.27 × 1039) and KAS (1.81 × 1040) models. The active pyrolysis zone was also noticed in the temperature range of 175–600 °C, which represents the maximum weight loss range as well in the present study.

Pyrolysis characteristics and kinetics of human faeces, simulant faeces and wood biomass by thermogravimetry–gas chromatography–mass spectrometry methods

Human faeces (HF) are treated as wastes in many parts of the world, a resource that can be converted to energy and fuels. To enhance the understanding of fuel conversion processes and decomposition characteristics, this study investigated the pyrolysis behaviour and evolved gas profiles of HF using thermogravimetry with gas chromatography–mass spectrometry methods. Kinetic parameters were deduced using model-free kinetic models. Results are compared with simulant faeces (SF), wood biomass (WB) and HF–WB blends. The pyrolysis of HF involved two decomposition peaks — a fronting peak with weight loss of ∼51 wt% and a tailing shoulder peak with weight loss of ∼15 wt%. The apparent activation energy for HF varied from 122–382 kJ/mol at conversion rates of 10%–90% using Kissinger–Akahira–Sunose model. Some of the key pyrolysis products for HF at 370 °C were 4-methoxy-phenol, n-hexadecanoic acid, phenol, 4-methyl- and indole isomer (pyrrolo[1,2-a]pyridine). At 530 °C, evolved gases were largely fragmented with high proportions of alkanes and alkenes including 3-dodecane, 2-undecane, 6-tridecene, 2-propenylidene-cyclobutene. These products differed to WB that are largely hydroxyphenyls and methoxyphenols with guaiacyl or syringil structures. Blending with WB improved pyrolysis of HF, irrespective of the proportions of blend.

Kinetic and thermodynamic analyses during co-pyrolysis of greenhouse wastes and coal by TGA

For thermal and kinetic analyses of co-pyrolysis of biomass and coal thermogravimetric analysis (TGA) is usually used to get valuable information for accurate design of co-pyrolysis facilities. In this study, pyrolysis mechanism of the equal mixture of tomato, pepper, and eggplant wastes as greenhouse vegetables wastes (GVW) and its blend with coal was investigated by using TGA with different heating rates. Kinetic and thermodynamic parameters were calculated by using Flynn-Wall-Ozawa (FWO) and Kissinger-Akahira-Sunose (KAS) models. To highlight the synergistic effect between GVW and coal during co-pyrolysis, the deviation between the experimental and calculated values of mass loss and mass loss rate was calculated. The average activation energy (Ea) of 100%wt calculated by FWO and KAS models was 74.27 and 67.00 kJ mol−1, whereas Ea of 0%wt was 133.99 and 129.84 kJ mol−1, respectively. The average Ea of 25%wt was 148.34 and 145.19 kJ mol−1, while it was 57.21 and 49.40 kJ mol−1 for 50%wt. The positive values of deviation indicated the existence of synergistic effect between GVW and coal during co-pyrolysis. The blend of 50%wt with the smallest Ea and ΔS was the best combination for the simultaneous valorization of GVW and coal through pyrolysis.

Isokinetic analysis on the oxidation of Jurassic coal: a case study of samples from Xinjiang, China

Jurassic coal samples from Liuhuanggou (LHG) and Wudong (WD) coal mines, Xinjiang Province, China, were selected for oxidative thermal energy experiments. A temperature-programmed experimental system measured the variation of gaseous products and the changes in thermal energy release with temperature. Thermokinetic parameters, namely the apparent activation energy (Ea) and pre-exponential factor (A), of the coal samples for four heating rates were determined using a thermogravimetric analyser. During the low-temperature oxidation stage, two samples had temperature curves characterised by their production levels of the index gas (CO); the temperature changes were approximately equal, but the critical temperatures differed. The WD sample produced less CO gas. However, the maximum and minimum exothermic strengths of the two samples had some similarities to the temperature change curves. The characteristic temperatures for the coal samples were discovered using different heating rates. For the WD sample, the characteristic temperature varied according to the heating rate, and the thermogravimetry (TG) and derivative TG curves of the samples lagged with an increase in the heating rate. The characteristic temperatures of the sample increased with the increase in the heating rate. Isokinetic analysis (the Flynn–Wall–Ozawa and the Kissinger–Akahira–Sunose models) was used to calculate the thermokinetic parameters of the sample. The range of the heating rates was 2 to 15 °C min−1 for oxygen concentration of 21 vol%, and the Ea of the samples decreased with the increase in the heating rate.

Characterization of Pyrolysis Products and Kinetic Analysis of Waste Jute Stick Biomass

Thermochemical process of biomass is being considered as a latest technique for the restoration of energy source and biochemical products. In this study, the influence of the different heating rates on pyrolysis behaviors and kinetic of jute stick were investigated to justify the waste jute stick biomass as a potential source of bioenergy. Pyrolysis experiments were carried out at four several heating rates of 10, 20, 30 and 40 °C/min, by utilizing the thermogravimetric analyzer (TG-DTA) and a fixed-bed pyrolysis reactor. Two different kinetic methods, Kissinger–Akahira–Sunose (KAS) and Ozawa–Flynn–Wall (OFW) were used to determine the distinct kinetic parameters. The experimental results showed that, the heating rates influenced significantly on the position of TG curve and maximum Tm peaks and highest decomposition rate of the jute stick biomass. Both the highest point of TG and the lowest point of Derivative thermogravimetry (DTG) curves were shifted towards the maximum temperature. However, the heating rates also influenced the products of pyrolysis yield, including bio-char, bio-oil and the non-condensable gases. The average values of activation energy were found to be 139.21 and 135.99 kJ/mol based on FWO and KAS models, respectively.

Pyrolysis kinetics and reaction mechanism of the electrode materials during the spent LiCoO2 batteries recovery process

The spent lithium-ion batteries (LIBs) have potentially serious environmental hazards but contain various valuable metals. Pyrolysis has been preliminarily proven to be an efficient method to dispose spent LIBs and recycle valuable metals. However, the kinetics and reaction mechanism during this pyrolysis process still remain unclear. Therefore, in this study, the pyrolysis kinetics and reaction mechanism of a typical spent LIB (LiCoO2 battery) was investigated and revealed in depth. The results indicated that the reactions happened to the electrode materials (LiCoO2, C) were mainly in the range of 500−800 °C. Two iso-conversion methods (Kissinger–Akahira–Sunose model and Flynn–Wall–Ozawa model) could both well describe the pyrolysis process, and the corresponding activation energies obtained were 389.61 and 405.67 kJ/mol respectively. The physicochemical properties of the pyrolysis products were detailedly characterized to reveal the reaction mechanism. The pyrolysis reaction mechanism of the electrode materials was firstly proposed and divided into three stages: firstly, LiCoO2 was decomposed into CoO, O2 and Li2O; then Li2O reacted with CO2 to form Li2CO3; finally CoO was reduced and converted into Co. This study is expected to provide a comprehensive understanding of the pyrolysis kinetics and reaction mechanism during the spent LiCoO2 batteries recovery process.